Integral motor and control

ABSTRACT

An energy efficient low-power integral electronically commutated fan motor and control circuit assembly mounted on a circuit board for use in refrigerators utilizing a Hall sensor to provide positional control signals for sequential energization of the windings with the Hall sensor energization being pulsed, and the motor stator windings energized only during a portion of the period, when rotational torque produced by the energization is greatest in order to reduce the power input to the assembly. Integrally molded multi-function components including the coil bobbin, ground pin, Hall sensor holder, motor bearing oil well covers, and assembly housing provide positioning, support, and securing assistance along with electrical and magnetic operative connections and positioning. A capacitively coupled bridge power supply is provided to further reduce power consumption, and the motor is protected under fault and stall conditions by a current limiting circuit and a timed retry circuit, and the rotor and stator are designed for adequate starting torque in a refrigerator. Power is supplied to the motor windings through a voltage dropping capacitor connected in series therewith.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to an integral, low power, highefficiency motor and control particularly suitable for use inapplications where high reliability and high efficiency are particularlyimportant, such as, for example, household refrigeration systems.

[0002] In conventional refrigerators of the residential or householdtype a compressor pumps a circulating refrigerant such as freon to acondenser coil where heat is extracted. The condenser coil is typicallypositioned on the exterior of the refrigerator, and air circulates overand around the condenser coils (with or without assistance from a fan orblower) to extract heat therefrom. The cooled refrigerant is thencirculated through an evaporator coil within the refrigerator, typicallyin a freezer compartment, to cool the space within the refrigerator. Therefrigerant then circulates to the compressor and thence back to thecondenser. This cycle continues until the temperature within therefrigerator reaches a desired preselected temperature as sensed by athermostat or temperature control. A small motor driven evaporator fanis normally provided within the freezer compartment to circulate airover the evaporator coils, through the freezer compartment, and betweenthe freezer compartment and the remainder of the refrigerator.

[0003] A conventional fan motor is typically a low power motor having apower input in the range of 8.5 to 13.5 watts with an Output power ofapproximately 2.5 watts. Thus, it will be understood that the efficiencyof conventional evaporator fan motors is generally in the order of lessthan 30%. It also should now be understood that 70% or more of theelectric power supplied to such motors is converted to heat within therefrigerator (or freezer compartment), and such heat must be removedfrom the interior of the refrigerator by the refrigeration system. Thus,inefficient evaporator fan motor operation is undesirably leveraged,because each watt of heat released in the freezer increases the coolingand thus power demands on the refrigerant compressor motor and theremainder of the system. Typically, with other things being heldconstant, the release of one extra watt of heat inside a refrigeratorrequires in excess of one extra watt of compressor motor power to removeeach such watt of heat generated within the refrigerator. Even with ahighly efficient refrigeration system it would typically require inexcess of 1.2 additional watts of input power to compressor andcondenser fan motors compensate for each additional watt of powerdissipated by an evaporator fan motor inside the refrigeratedcompartment. This amounts to a total power leverage factor of 2.2.

[0004] One major objective of the present invention is to provide a newand improved motor and control such that the just referred toundesirable leverage can be viewed as desirable, and used to reduce theoverall power consumption by a refrigeration system. For example, if onewere able to reduce evaporator fan motor input power requirements by aninitial 8 watts per hour, then one could reduce the overall refrigeratorpower requirements by the initial 8 watts plus an additional 7 or morewatts (at the compressor and condenser) and this all could amount to asmuch as 90 kilowatt hours per year, which could represent as much as 10%of the total annual power consumption of a typical householdrefrigerator.

[0005] This power reduction is significant, however, not only in itscost savings to a consumer over the life of a refrigerator, but also inhelping to reduce the burning of fossil fuels to generate such power.Moreover, the power savings just mentioned can assist in enabling arefrigerator to meet the power reduction regulations and/or incentivesof state and federal governmental bodies.

[0006] Public concern about electrical power consumption, is reflectedby proposed legislation and U.S. Department of Energy (DOE) regulations,and has emphasized the need to increase the efficiency of householdappliances to reduce both the amount of fossil fuel burned, and the needfor additional power generation capacity. Public interest and demand isreflected in Energy Guide labels or tags on household appliances whichdisclose the power requirements and typical cost of operationinformation.

[0007] A still further complication in the redesign of some motors, andparticularly refrigerator evaporator fan motors, is the need that thesubstitute motor fit within the space envelope available in presentrefrigerator designs, since it would be costly to change existingtooling used in manufacturing refrigerators simply to accommodatedifferently sized motors. Moreover, it is desirable to utilize a highefficiency motor to replace an existing motor for repair purposes. Thus,it is very desirable that improved motors (and controls when packagedtherewith) be usable in existing space envelopes.

[0008] In addition there is growing concern over release into theatmosphere of freon refrigerants used in refrigerators and of chemicalsused as foaming agents during the manufacture of insulation used inrefrigerator walls. Concern over the possible damage to the ozone layerin the earth's atmosphere by CFCs (chlorofluorocarbons) in therefrigerant is leading to the use of alternate refrigerants. However,presently available alternate refrigerants are less efficient than thefreon presently used, so their use would further reduce the efficiencyof refrigeration systems. Moreover, the foam insulation used in thewalls of refrigerators typically utilizes CFCs as the blowing agentduring manufacture, while the use of other known substitute materialsresult in insulations with reduced R factors. This all further increasesthe desirability of reducing the amount of heat released by a motorinside a refrigerated enclosure.

[0009] The need to further increase the efficiency of electricappliances has led to cash incentives. Various state or local agenciesor utility companies (such as in California) offer rebates to newappliance purchasers proportional to the amount of energy saved by usingthe new appliance. This further increases the continuing demand and needfor refrigerators and other appliances with increased efficiency.

[0010] As a result of the above considerations considerable research andeffort has gone into the redesign of appliances, including componentsthereof such as motors, in order to increase electric efficiencies, andto meet present or anticipated environmental concerns, with regulationsand goals aimed at reducing power consumption by as much as 30%.

[0011] Thus, it would be extremely desirable to provide an improved highefficiency fan motor for a household refrigerator which also could beused (with or without modification) as a refrigerant condenser fanmotor.

[0012] Improved low power motors of the type we contemplate for use inrefrigeration systems may advantageously be of the “brushless dc” or“electronically commutated motor” type. However, this type of motor canbe damaged if the motor stalls, or ceases to attain desired operatingspeeds when first starting, or rotates at lower than normal speeds underload conditions. In the absence of a back emf or voltage associated withrotation of the rotor, the applied line voltage may cause excessivecurrent flow through the motor windings which may exceed the ratedcurrent carrying capacity of the windings and lead to over-heatingand/or failure. Accordingly, it is desirable to provide adequatestarting torque, and it is also highly desirable to provide means todetect motor stall, and to provide adequate restarting torque and/orcurrent limiting in the event of motor stall.

[0013] Notwithstanding all of the above, in highly competitive marketssuch as, for example, the household refrigerator market it is also veryimportant to keep the cost of improved motors to a minimum since manyconsumers are unwilling, or unable, to pay higher prices for energysaving improvements, notwithstanding the fact that initial costs oftenare recouped many times over the multiple year life of a machine. Thus,it is important that initial costs for improved products be minimized byproviding a readily manufacturable design.

[0014] Also, notwithstanding all of the above, it is very important thatmotors for equipment having a long service life (e.g., householdrefrigerators) exhibit reliable operation and have a long life in viewof consumer expectations and past experience with equipment thatrequires little or no maintenance for extended periods of continuoususe. We have determined that brushless motors combined with solid statecontrol device circuitry can provide the desired good reliability andlow maintenance operation.

OBJECTS AND SUMMARY OF THE INVENTION

[0015] Accordingly, a primary object of the present invention is toprovide a new and improved, integrated and unitary motor and associatedcontrol circuit elements having improved operating efficiency.

[0016] Another object of the present invention is to provide a new andimproved low power integrated and unitary motor and associated controlcircuit elements suitable for use in refrigeration systems which is costefficient in operation, yet relatively inexpensive to manufacture inorder to minimize the initial cost of the system.

[0017] Still another object of the present invention is to provide a newand improved integrated and unitary low power fan motor and associatedmotor control circuit which is suitable to be used as the condenser orevaporator fan motor in refrigeration systems.

[0018] Yet another object of the present invention is to provide animproved high efficiency low power fan motor and control for use inrefrigeration systems which provides adequate starting torque and whichdetects and protects the motor in the event of motor stall.

[0019] Still yet another object of the present invention is to provide alow power motor and control circuit in which the fan motor andassociated control circuitry elements are combined in an integrateddesign with unified construction and, structural support, and which maybe installed in the space in a refrigeration system normally occupiedheretofore by only a motor; thus promoting the possibility of directreplacement of existing motors in existing refrigeration system designs.

[0020] A further object of the present invention is to provide a new andimproved low powered integrated motor and control circuit which isreliable in operation, and which is relatively maintenance free.

[0021] Still other objects relate to the provision of a combination ofcontrol circuit elements and an electric motor that is of novelmechanical construction, electromagnetic design, and arranged in aunitary package.

[0022] In order to attain the above and other related objects, incarrying out the present invention in one form thereof, a direct currentelectronically commutated DC fan motor is integrally assembled on acircuit board that also carries control circuit elements, with a portionof the motor passing through a region of the circuit board, with astator coil positioned to one side of the rotor; and with electroniccomponents positioned to the other side of the rotor.

[0023] The components of the assembly include integrally moldedmultifunction components which assist in the positioning, supporting andretention of various electrical and electronic components in properoperative positions. The coil is wound on a bobbin which includesintegral means for positioning and securing the coil on the circuitboard, to accommodate self-connecting winding terminals which alsoposition, connect, and support the coil on the circuit board, and meansfor positioning and detachably securing the assembled fan motor andcontrol circuit within the assembly cover or housing, while at the sametime preventing movement of the assembly in orthogonal directions.

[0024] Motor oil well covers include integrally molded members thatfacilitate attachment to the motor end shields while also providing atwo point axial support system for the integral motor and controlassembly within the refrigeration system.

[0025] Preferred embodiments of our invention include a low powerbrushless motor control that utilizes a Hall device to sense the angularposition of the rotor to control the commutation of the windings. TheHall sensor is preferably pulsed during a portion of each cycle ofoperation and its output is sampled for operation and control of themotor in order to provide increased efficiency. It also is preferred touse solid state control circuitry to energize the field coils of themotor only during the periods of their greater efficiency during eachpower cycle, and discontinuing the energization during the periods oflowered efficiency in order to further realize enhanced powerefficiency. Another preferred embodiment of the present inventionrealizes still further efficiency improvements through the use of acapacitor-feed bridge circuit coupling of the control circuitry to powersemiconductors that energize the direct current motor.

[0026] A stall or speed sensor is also preferably provided to detectdecreased motor speed and motor stall, and apply a periodic startingtorque pulse; and also to limit the magnitude and duration of currentflow through the motor under fault conditions.

[0027] Other objects of the present invention and the advantagesrealized therefrom will become readily apparent from the followingdescription taken in conjunction with the accompanying drawings in whichlike reference characters are used to describe like parts throughout theseveral views.

BRIEF DESCRIPTION OF DRAWINGS

[0028]FIG. 1 is a perspective view, partially cut away, of a typicalhousehold refrigerator incorporating a motor and control embodying thepresent invention in one form thereof;

[0029]FIG. 2 is a block diagram of the refrigeration system embodied inthe refrigerator of FIG. 1;

[0030]FIG. 3 is a perspective view of the integrated unitary evaporatorfan motor and associated control circuit elements of FIG. 1;

[0031]FIG. 4 is a rotated perspective view of the bottom of the packageshown in FIG. 3;

[0032]FIGS. 5 and 6 are exploded views of various major components ofFIGS. 3 and 4;

[0033]FIGS. 7 and 8 show the permanent magnet rotor assembly of FIGS. 5and 6, with FIGS. 7 and 8 both drawn to a scale of about 1.90 times fullsize;

[0034]FIG. 9 shows details of the stator construction of the motor ofFIG. 5, drawn to a scale of about 1.29 time full size;

[0035]FIG. 10 is an enlarged fragmentary drawing of a portion of FIG. 10showing the placement and retention of a Hall device sensor within thestator, drawn to a scale of about 4.63 times full size;

[0036]FIG. 11 is a fragmentary drawing of portions of the DC brushlessmotor of FIGS. 3-9 showing the stator bore configuration andpolarization of the permanent magnet rotor, and is drawn to a scale ofabout 2.12 times full size;

[0037]FIG. 12 is an enlarged view which shows details of themultifunction coil bobbin part of the motor of FIG. 5;

[0038]FIG. 13 shows details of the coil windings on the coil bobbin ofFIG. 12, all drawn to a scale of about 1.83 times full size;

[0039]FIG. 14 and enlarged fragmentary FIGS. 15A and 15B show details ofends of the coil windings (of FIG. 13) fastened to terminals, and thesecuring of terminals and windings directly to the conductive runs of acircuit board;

[0040]FIGS. 16, 17 and 18 show details of the integral mounting andpositioning means on the assembly cover, with FIG. 18 being a crosssection of FIG. 16 along the line 18, 18;

[0041]FIG. 19 is a cross-sectional view of FIG. 3 taken longitudinallythrough the axis of rotation of the motor, drawn to a scale of about1.43 times full size, and showing details of the unitary motor assemblyand control circuitry and circuit elements;

[0042]FIG. 20 is a much enlarged cross section taken through the centerof the Hall sensor showing details of the positioning and mounting ofthe Hall sensor of FIGS. 5 and 19;

[0043]FIG. 21 is a schematic of the solid state circuitry associatedwith the Hall sensor and motor field coils, portions of which are shownon FIGS. 4, 5, 15A, 15B, 19 and 20;

[0044]FIG. 22 and associated FIGS. 22A, 22B and 22C are block and logicdiagrams of the circuitry of an integrated circuit device, shown in FIG.21, used to control the pulsed energization of the Hall sensor and themotor field coils; with FIG. 22 showing the relationship of the circuitsof FIGS. 22A, 22B and 22C; and

[0045]FIG. 23 is a plot of motor winding current flow and thetorque/power output of the assembly of FIG. 19.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] In FIG. 1, a refrigerator 10 is shown incorporating oneembodiment of the present invention. The refrigerator includes parallelouter walls 2 and inner walls 4 (with the space therebetween filled withfoam insulation 5) and an upper freezer compartment 6 and a lowerrefrigerator compartment 8. Doors 12 and 14 provide access to thecompartments 6, 8. An integral or unitary evaporator fan motor andcontrol circuit assembly 1 which includes a motor and associated controlcircuit elements is positioned at the rear of the freezer compartment 6and includes a protective housing or cage (not shown) enclosing a fan 20fastened to the shaft 18 of the motor 16 which is described in detailbelow. Although the exact air flow path may be different for differentrefrigerator designs, in the equipment shown in FIG. 1, refrigerated airis circulated within the freezer compartment 6, and through slots 24,26, and 28 in the bottom of the freezer compartment into therefrigerator compartment 8.

[0047]FIG. 2 shows the interconnection of the major components of thehousehold refrigeration system of FIG. 1. The interior of refrigerator10 includes a thermostat or temperature sensor 23 which controlsoperation of the motor 29 which drives compressor 27. The motor 29 maybe of electronically commutated type, if desired, through use ofelectronic commutator 25. Copending U.S. patent applications, filed Feb.27, 1991, entitled “Motor Controls, Refrigeration Systems and Methods ofMotor Operation and Control,” Ser. Nos. 07/661,807 and 07/661,818, byDavid M. Erdman, one of the inventors of the present patent application,assigned to the same assignee as the present patent application, and theentire disclosure of which is incorporated herein by reference, disclosedetails of an electronically commutated motor for refrigerationcompressor use which is suitable for use in the manner depicted in FIG.2.

[0048] The compressor 27 circulates a refrigerant such as freonsequentially through the condenser coil 46, expansion valve or nozzle31, and the evaporator coil 30 to cool the compartments 6 and 8 (seeFIG. 1) within refrigerator 10. An evaporator fan motor 16 and theevaporator coil 30 are located within the refrigerator interior 6,8,typically in the freezer compartment 6, and fan 20 driven by the motor16 blows air across and through the evaporator coil to reduce thetemperature of the air. The brushless direct current (DC) motor 16 isdriven by an electronic commutator control circuit 33 packaged as aunitary component with the motor 16 (as described in detail below) andis energized by power supplied along lines 36 and 37 (upon closure oftemperature sensor 23). A second brushless DC motor 40, may be poweredby electronic commutator 42, if desired, to drive condenser fan 44 toblow cooling air over the condenser coil 46. The condenser coil 46, fan44 and condenser fan motor 40 are normally positioned on the rear wallof, or at the bottom of, the refrigerator 10 (outside the refrigeratorinterior), and the condenser fan motor is energized during the timeperiods when the compressor motor 29 is energized. Thus, temperaturesensor 23 controls the periodic demand energization of the compressormotor 29, evaporator fan motor 16 and condenser fan motor 40.

[0049] Referring next to FIGS. 3, 4, 5, 6 and 19, the major componentsof the assembly 1 are positioned on and within a housing, enclosure, orassembly cover, 50, fabricated of inert resilient plastic to provide aninert and electrically insulating housing. Housing 50 provideselectrical isolation and insulation of the electronic circuit componentsto comply with the “finger probe” test and thus helps prevent accidentalshock by a consumer or serviceperson. The cover 50 is alsoflame-resistant because of the electronics involved, and “pure” from ahealth consideration because of the presence of food along with moisturewithin the refrigerator. A suitable material meeting all thoserequirements has been found to be a polyvinyl chloride available as Geon87-241 from the B. F. Goodrich Co. Positioned within the housing 50 isthe stator 52 and rotor 54 of motor 16 with the rotor positioned withinthe central region of the housing. The laminated stator core 360 extendsinto one end region of the housing cover 50 with the coil bobbin 56 andstator coil 58 positioned around the laminations of coil core 390.

[0050] Also positioned within the housing 50 and located below hingedcover 60, on the side of the rotor 54 opposite coil 58, are electroniccomponents such as control circuit elements 200 and 361 (see FIGS. 5 and16-19) on printed circuit board 336, which are protected and isolated bythe hinged cover. The hinged cover 60 rotates about hinge 62 that ismolded as an indented seam or crease integral with and part of thehousing 50. Resilient fingers 64 and 66, also molded integral with thehousing 50, on each end of hinged cover 60, extend through slottedpassages 68 and 70 molded in the sides of the housing 50. The resilientfingers 64 and 66 are contoured to provide a camming action such thatthe application of manual pressure to the hinged cover 60 forces theresilient fingers or jaws 64 and 66 toward one another until the taperedextensions 74 and 76 extend through the slots 70 and 72, whereupon theysnap away from each other and overlie the inner ends of slots 68 and 70,respectively, securing the hinged cover firmly in place. The hingedcover 60 may be opened by applying pressure to the tapered extensions 74and 76 of the resilient fingers 64 and 66, respectively, such that theymove toward one another after which they can be withdrawn through slots68 and 70, respectively, to the open cover position.

[0051]FIG. 4 shows the bottom of the housing 50 which has been rotatedfrom the position shown in FIG. 3 to better illustrate features of itsconstruction. It is to be noted that the tapered extensions 73 and 75molded integral with the bobbin 56 (also see FIG. 12) on which thewindings of coil 58 are wound are shown positioned within slots 78 and80 in the end of motor housing 50. When the integral motor and controlcircuit assembly 1 is pushed into the assembly cover 50 (also see FIGS.16-18), the tapered surfaces of extensions 73 and 75 provide a cammingaction which initially deforms the end 84 of the resilient assemblycover outward, enabling the assembly to be inserted into the assemblycover until the extensions enter the slots 78 and 80. The resiliency ofthe deformed end section 84 of assembly cover 50 then causes the endsection 84 to snap back to its original position and surround thecamming extensions 73 and 75, locking the motor and control circuitassembly 1 within the cover, while at the same time assisting inproperly positioning and securing the various elements of the assemblywithin the housing.

[0052] Circuit board 336 (see FIG. 19) defines a substantially enclosedchamber 562 between the circuit board and the bottom 102 of the motorhousing 50. As best shown in FIGS. 4 and 5, aperture 93 on the side ofassembly cover 50 provides access, for the detachable edge connectorpower plug 106, to the circuit board traces 108, 110 and 112, formed aspart of the circuit runs on board 336. Input power and groundingconnections are provided to the assembly 1 through power plug 106. Aslot 114 extending into the bottom 102 of housing 50 limits access to,and cooperates with, the resilient thumb release mechanism 107 of edgeconnector plug 106 to ensure that the plug can only be inserted withproper orientation. Slots 114 also assist in guiding the plug to ensureproper connection with and positioning with respect to board 336. Theplug 106 is secured in place, in proper position, by depressing thumbpiece 115 of the mechanism 107 while the plug 106 is being inserted.This rotates or pivots the mechanism to raise the cylindrical lockingportion 117 until it clears aperture 370 in the board 336, where-uponthe locking portion may move into, and be secured within, aperture 370upon release of the thumb piece 115.

[0053] Note that the bottom 102 of housing 50 includes a circularopening 90 in the central region thereof (see FIGS. 4, 5 and 16-18), andeight radially extending slots 92 extend outward, away from the centeror axis 437 of opening 90. This results in a leaved spring configurationmolded integrally with the housing 50, that provides a plurality ofresilient tapered fingers 94 formed between each adjacent pair of slots92. The ends of fingers 94 are dimensioned and curved to receive, grasp,and position the cylindrical or tubular extension 96 of the oil wellcover 518 of the motor, with extension 96 being molded integral with theoil well cover. The extension 97 is in alignment with, and opposite, asimilar extension 122 (also see FIG. 19) on oil well cover 516 throughwhich the shaft 18 passes. The extensions 97 and 122 on opposite ends ofthe rotor of the motor 16 constitute one way of mounting the assembly 1within a refrigerator, and are positioned within cylindrical openings,or bearings (not shown), in a refrigerator to provide a two-pointfloating support which reduces evaporator fan motor vibration and noisewithin the refrigerator. This simple yet integral support system enablesready replacement of existing evaporator fan motors with motorsillustrated herein for repair purposes, or for incorporation intoexisting refrigerator designs.

[0054] The assembly 1 has relatively few parts in order to minimizemanufacturing costs, including the cost of materials and assembly, andin order to provide an inherent increase in reliability. The assembly isuncomplex, and utilizes multifunction structural elements whichaccurately position, support, and secure the mechanical and electroniccomponents in operative relationship relative to each other.

[0055] The housing 50 supports and provides electrical isolation andinsulation for electronic components mounted on both sides of theprinted circuit board 336 (in the illustrated embodiment). These include(see FIG. 5) capacitor 361, Hall effect sensor 439 within Hall deviceholder 338, and other electronic components such as capacitor 357,capacitor 359, and IC 200 positioned on one side 340 of the board. Otherelectronic components such as power mosfet 560 (see FIG. 19) arepositioned on the opposite side 341 of the board 336 along with theprinted circuit interconnections or runs 499 (see FIG. 15A). Thecomponents are electrically isolated and insulated by being positionedin a chamber 562 defined by the board 336 and the bottom 102 of thehousing 50. As will be understood, leads such as lead 342 of metal oxidevaristor 3611 (see FIG. 19) extend from the electronic componentsthrough the board 336 and are connected in circuit with electroniccircuitry and components supported on one or the other sides of theboard.

[0056] It is to be noted that the electronic components such as the ASIC200 and the Hall device are positioned on board 336 to one, or a first,side of the large aperture 344 in the central region of the printedcircuit board. The rotor 54 of the evaporator fan motor 16 is positionedin the region of, and so that the rotor shaft passes through, aperture344; while the stator coil 58 and coil bobbin 56 are positioned to theother, or a second, side of the aperture 344, remote from capacitor 361and Hall device holder 338. This general layout and structure permits atwo-point floating suspension of the rotor about axially extendingtubular portions or noses 97 and 122 of the oil well covers. Thisarrangement also assists in providing a compact, integral assembly whichfits within the space available in existing refrigerator designs forexisting evaporator fan motors.

[0057]FIGS. 5, 10, 11, 19 and 20 show multifunction parts associatedwith the Hall sensor 439 for positioning, supporting, and connecting theHall sensor in an operative interrelationship with both the motor andvarious control circuit components. The Hall device holder 338 ispositioned on and secured to board 336 (see FIGS. 5 and 20) by means ofa pair of tubular extensions 550 molded integral with the holder 338 andthat pass through holes in the board. Hall device leads 342 are solderedinto the circuit runs on the bottom or reverse side 341 of board 336 andhelp provide positive and secure positioning of the Hall device 439,while also establishing electrical connections with other components ofthe control circuit. As seen in FIG. 5, the shoulder 354 and extension356, both molded integral with the holder 338, provide guidance,positioning or alignment, and support for the stator core 360 of themotor 16. When the stator 52 is assembled with the circuit board 336,the extension 356 extends into opening 358 in the stator core 360 untilthe shoulder 354 seats against the stator core, thus ensuring a positiveand preselected operational magnetic coupling between the Hall sensor439, a preselected region the stator core, and the rotor 54operationally located in bore 388 of the stator core.

[0058] FIGS. 6-8 show details of the fabrication, structure and supportof rotor 54. The currently preferred method of forming the permanentmagnet rotor 54 represents a modification of the approaches described inU.S. Pat. No. 5,040,286 issued Aug. 20, 1991 to William H. Stark,assigned to the same assignee as the subject patent application, and theentire disclosure of which is incorporated herein by reference. Morespecifically, we presently utilize a deep drawn stainless steel cup“can” 302 which includes an essentially closed end 306 having acentrally located aperture 304 through which the PE (pulley end) ofshaft 18 passes. The sidewall 310 of the cup 302 surrounds the magnets316, 317, and 318; and the laminated iron or steel core 320 to whichthey are adhesively secured, with the circumferential magnets andmagnetic core being sandwiched between Mylar® washers 322, 324. Astainless steel end washer 326 closes the open end of cup 302. Inpractice, and as revealed in FIG. 7, cup 302 is pressed over washer 322,circumferential magnets 316, 317 and 318, core 320, washer 324 andwasher 326, in essentially the same manner taught in U.S. Pat. No.5,040,286. The open end of cup 302 is rolled to provide a lip 330 (seeFIG. 8) extending around the edge of washer 326 to permanently containthe parts shown in FIG. 8.

[0059] The cup 302 and washer 326 mechanically protects the ferritemagnets 316, 317 and 318 against chipping, defoliation, and adhesivejoint failure. If any particles should separate from a main body ofsintered high-density magnet material, the surrounding steel structurewill contain such particles. The cup 302 is {fraction (6/1,000)} of aninch (0.15 mm) thick. It also has been found to be advantageous to use ahot melt adhesive to fill the voids or gaps along the edges of themagnets 316, 317 and 318.

[0060] With reference to FIGS. 5 and 6, sintered porous bronze sleevebearings 509, 504 support the shaft, and are supplied with oil from feltoil wicks 506 and 508 which are carried in chambers within the oil wellcovers 516, 518 which include oil well cover bases 514, 515 which snapinto place so as to trap oil wicking material 506, 508 within the oilwell covers. End shields 510, 512, in turn support the bearings and oilwell covers. The oil well covers 516 include fingers 522 that snap inplace in slots 524 in the end shields. Tapered portions 528 facilitateassembly, and ledges 529 prevent inadvertent disassembly of the oil wellcovers.

[0061] As best shown in FIGS. 6 and 19, a conventional snap ring 540snapped into a groove 541 on the shaft limits axial movement or end playof the rotor 54 in one direction. An end play bearing or thrust washer542 limits rotor end play in the other direction. The end shields 510and 512 also include tabs 532 (best shown in FIG. 6) which interfit withnotches 536 (see FIG. 5) on the core 360, and are held in place by anepoxy adhesive.

[0062]FIGS. 4, 6 and 19 also illustrate some of the multifunctionalpositioning and support aspects of the OPE oil well cover 518. Referringto FIG. 6, spacer ribs 566 (molded integral with the cover) extendradially outwardly to provide a spacing, or stand-off function withrespect to the bottom wall of housing 50 (as seen in FIG. 19), anddetermine the spacing of the subassembly above bottom 572 of assemblycover 50 to form the chamber 562 for the electronic components.

[0063] Referring to FIGS. 5 and 9-11, core 360 and conventionalinterlocked laminations 424 are stacked together to form a preselectedstack or core height. Each lamination includes a central opening thatforms a rotor accommodating bore 388. As best shown in FIG. 9, weprovide diametrically opposed arcuate portions 427 and 433 having adiameter of about 1.32 inches (33.5 mm). The portions 427, 433 have anarcuate extent, alpha, between steps 431, 429 and vertical axis 315 ofabout 130 to 140 degrees. In what we presently believe to be our bestmode, the angle alpha is 140 g. We also provide diametrically opposedbore defining stepped portions 428, 434 with a diameter of about 1.42inches (36.1 mm) that extend from steps 429 and 431 toward axis 315.However, in the vicinity of gap 358, region 428 ends at such gap; and inthe vicinity of step 430, region 434 becomes a straight line for adistance F (see FIG. 11) of about 0.244 of an inch (6.2 mm). Thus, thedepth of the steps 429, 431 is about 0.050 of an inch (1.27 mm). Thespan, theta, for these steps is 40° to 50°, and preferably 40°. The flatportion of the bore (see distance F in FIG. 9) provides an anomaly inthe flux path at one end of axis 315 that is believed to reflect orbalance the anomaly in the flux path caused by gap 358 at the other endof axis 315. The details of the bore design presented herein arebelieved to significantly enhance the starting torque or startingability of motor 16.

[0064] Our inventions are embodied, in the motor 16, in a relativelysmall C-Frame or “skeleton” motor having dimensions, as shown in FIG. 9,such that: the round bore diameter D was about 1.32 inches (33.53 mm);the overall width W of a lamination was about 2.5 inches (63.5 mm); theheight H was about 1.98 inches (50.3 mm); the winding window openingwidth 0 was about 1.44 inches (36.6 mm); the winding window height L wasabout 0.51 inches (12.9 mm); the leg width LW was about 0.53 inches(13.5 mm); and the coil core width CCW was also about 0.53 inches (13.5mm). The core stack height CSH (see FIG. 19) was varied, to producemotors of different power output capabilities, and in the case of a 3.8watt input/2.6 watt output motor CSH was about 0.3 of an inch (7.62 mm),while in the case of a 5.5 watt input/4.0 watt output motor, CSH wasabout 0.5 of an inch (12.7 mm). Thus, relatively small C-Frame motors ofthe type illustrated herein are producible having actual efficiencies of68% to 73% for core stack heights of 0.3 and 0.5, respectively. Thiscompares with prior art C-Frame motors of similar physical size (withroughly similar contents of lamination iron and copper wire content andthat are commonly known as KSP, or shaded pole AC induction motors)with, efficiencies of about 30%. For completeness of disclosure, it isnoted that the just described 0.3 and 0.5 inch stack motors were made oflaminations stamped from lamination grade silicon steel; and that thecoil wire size, turn count, and size of capacitor in different caseswere as shown in Table I hereinbelow.

[0065] Payback from improving efficiencies for motors mounted insiderefrigerated spaces is enormous. For example, a current refrigeratoruses a KSP motor that requires input of 13.5 watts, most of which isconverted to heat. Motor type 3 listed in Table I can be interchangedfor such KSP motor and do the same air circulation work yet require only5.5 watts of input power (8 watts less input). In the particularrefrigerator being discussed the savings leverage factor is about 2.2(considering the compressor and condenser). Thus, a total system powersavings of (8+1.2×8) or 17.6 watts is realized. In other words, the airmoving work of the old motor is performed while the actual energyconsumed by the system is actually reduced by an amount greater than thetotal power input of the old motor. TABLE I Motor Number 1 2 3 DataDetermined By: Calculation Test Test Core Stack Height (inches) 0.3 0.30.5 (mm) 7.62 7.62 12.7 # Of Wire Turns Per Coil 2300 2300 1950 Total #Of Wire Turns 4600 4600 3900 Bare Wire Size, AWG. 32 32 31 Bare WireDiameter, (inches) 0.008 0.008 0.0089 (mm) 0.203 0.203 0.226 Size OfSeries Capacitor 127 2.1 3.4 3.7 In Microfarads RPM At Load Point, 28502850 3250 rpm Torque At Load Point, 1.05 1.25 1.65 oz-in Watts Output2.2 2.6 4.0 Watts Input 3.25 3.8 5.5 Efficiency 68% 68% 73%

[0066] The data of Table I above clearly shows (compare the data formotors 1 and 2) how a change in the value of capacitor 127 can be usedto change the power input and torque output. Thus, our motor and circuitis such that a motor-control designer now can tailor the output of amotor by simply changing a control circuit capacitor. A comparison ofthe data for motors 2 and 3, on the other hand, reflects how bothgreater power output and speed changes can be accomplished by changingthe core stack height, the number of coil turns and wire size, and thesize of a control circuit capacitor. Thus, motor-controls made pursuantto our teachings may be readily modified, in a simple and straightforward manner, to obtain a range of desired operating characteristics.

[0067] The above described bore configuration is an important factor inproviding improvements in starting capabilities, and it can be generallycharacterized as one wherein a first flux path anomaly is located at apreselected location on one side of the bore as a consequence ofaccommodating a position sensing device (e.g., openings or pocket 358for device 439); a second flux path anomaly is located about 180° awayfrom the first anomaly (e.g., a flat region 435); and regions of limitedspan that represent basic bore dimension discontinuities (e.g., steps)to assist in starting without unduly degrading efficiency.

[0068] With reference to FIGS. 9 and 10, the pocket or chamber 358 is ofgenerally rectangular shape, with a taper partially closing the innerend adjacent the bore 388, and the chamber extends through the core,parallel to axis of rotation 437.

[0069] An open region 53, defined by lamination legs 440 and 442 isprovided to accommodate the excitation windings in the stator coil 58(also see FIG. 5). Lamination leg ends 444 and 446 mate with matchingconcave openings 447 in the coil core 390 (see FIG. 13) Referring nextto FIGS. 12-15, coil bobbin 56 includes a central section 450 havingwalls 452, 454 that define a coil core accommodating passage 456. Anysuitable bobbin material may be used, and in our reductions to practice,we have used Dupont's material known as Rynite 415HP, which is readilymoldable and provides good electrical and mechanical properties.Integrally molded bobbin end plates 460, 462 retain the wound coil inplace, and also establish connector locations. Also molded integrally,as part of the bobbin 56, are locating anchors 384, 368 which helpsecure together the motor and circuit board 336. Also molded as part ofthe bobbin 56 are camming fasteners 73, 75. Tapered camming extensions74, 76, assist in positioning the assembled motor and control board,within the housing 50 as described hereinabove.

[0070] As shown in FIGS. 13-15, windings 59, 61 of coil 58 are layerwound separately. The use of two separate windings simplifies theswitching circuitry used to establish the desired direction of currentflow through the windings as the north and south poles of permanentmagnet rotor 54 approach, and then move away from, a given region of thestator 52. It is not necessary to switch direction of current flowthrough the windings, since switching energization from winding 59 towinding 59 (and vice versa) switches the polarity of the magnetizationas required without complex switching circuitry. While conventionalwisdom might indicate that a bifilar winding would be preferred to twoseparate windings, extensive testing has suggested that to do so wouldincrease the risk of phase-to-phase shorting of bifilar wound windings,and particularly under high humidity conditions. Thus, a layer windingapproach is preferable for refrigeration applications. Winding 59 isseparated from winding 61 by a single wrap of 3M, #1 Dysular tape; andthis same tape or a fiberglass tape is then wrapped around the outsideof the winding as shown at 61.

[0071] Slotted pockets or receptacles 470, 472, 474 and 476 includeperpendicular slots 480, 482, 484 and 486. This divides each slottedpocket 470, 472, 474 and 476 into a separated pair of jaws with adequateresiliency and flexibility to enable the forced insertion and retentionof an electrical terminal 486 into each of the slotted pockets. Tofacilitate the positioning and retention of terminals, the terminalseach include jaws 488, 490 and, upon forced insertion of the terminals,a camming action between the tapered jaws and slotted receptaclesresults in an interference fit therebetween.

[0072] Passageways 490, 492 assist in guiding, positioning, andprotecting winding ends 59, 61, which lie along the passageways, lieacross the slotted pockets 470, 472, 474, and 476, and are wrappedaround an adjacent post 506 (see FIG. 13). Thus, when terminals 486 areinserted into the pockets, the sharp inner opposed edges of jaws 488 and490 pierce the insulation on the magnet wire ends so as to provide agood electrical connection between the magnet wire and the terminal.

[0073] The projections 498 of terminals 486 become connection pointswith the circuit board. Thus, the terminal tips 498 pass through holes374, 376, 378, 380 in board 336 and also through holes in runs 499 onthe opposite side of the board. FIG. 15B shows solder connections 501between tips 498 and conductor runs 499. In addition to providingelectrical connections, this technique mechanically secures theterminals and thus bobbin 56 and the rest of the motor to board 336.FIGS. 15A and 15B also show how the posts 384 are headed over to providefurther mechanical integrity for the assembly.

[0074] It is again emphasized that various components of the assemblydisclosed herein include multifunctional means that, e.g., position,connect, and/or support various components in operative relationshiprelative to one another. For example, the Hall device holder 338 (seeFIGS. 5, 9 and 20) holds the Hall device in a desired operative relationwith the stator core, is mechanically locked to the circuit board, andalso mechanically stabilizes the position of the stator. The Hall devicenot only helps anchor holder 338 to the board, but also senses rotorposition (and rotation) as described in detail below.

[0075] Further details of a preferred permanent magnet rotorconfiguration are shown in FIGS. 6 and 11. The rotor 54 includes acylindrical magnetic core 319, that is of conventional laminatedconstruction, surrounded by three circumferentially extending arcuateferrite magnet segments 316, 317, 318, each of which theoretically spans120°, but actually spans approximately 118 degrees (approximatelyone-third of the rotor core surface) since allowances must be made formanufacturing tolerances, variations in part sizes, and so forth.Ideally, one continuous cylindrical magnet should be used, but such aconstruction would not be practical because of: wide dimensionaltolerances that are inherent in ceramic materials such as ferritemagnets; the brittle and easily damaged character of ceramic materials;assembly and manufacturing difficulties that would be presented, and soforth. It is believed that these also are reasons to not make thepermanent magnet part of the rotor from only two magnet pieces.Moreover, we have discovered that, for a two-pole motor, three magnetsshould optimally be provided, but magnetized into a two-poleconfiguration to form a rotor having only one north and one south polarregion centered on the axis 323 of rotor 54. The left and right portions331, 332 of the stator core constitute magnetic poles, centered on thestator polar axis 325, that are supplied with magnetic flux from thecoil core 390, and these portions alternately become excited north andsouth magnetic poles. Also, and as will be understood by persons skilledin the art, Hall device 439 senses changes in polarity of the rotor asthe rotor magnets rotate past the device 4391. As the transition region,T, between north and south rotor poles passes the Hall device, thedevice provides a signal used for switching power to the windingscarried by the coil core 390, thereby to switch the polarity of thestator poles.

[0076] The provision of three magnet segments (for a two-pole rotor) andthe magnetization of the rotor as shown in FIG. 11 is, we believe, ofsubstantial significance for reliable operation of motor 16. It is knownthat the Hall device will provide a signal as the regions T movetherepast. It also is believed that the slower the rotor 54 is moving(e.g., when first starting), the more important it is that the signalfrom the Hall device be “clean” and be accurate in sensing the positionof the rotor. Also, we have found that “cleaner” signals and morereliable starting will occur when the transition region T between rotormagnetic poles is positioned at least thirty degrees (30°) from themagnet void or gap 337, 339, or 341 closest thereto. The use of threerotor magnets, with the north-south pole transitions T located about 30°from a void between adjacent magnets provides a readily manufacturablerotor that also yields reliable starting performance.

[0077] In the particular arrangement of rotor 54 it will be noted thatthe above criteria will result in the center of either the north orsouth rotor poles being located at or very close to one of the gaps.However, this does not result in any difficulties known to us.Application of the above described principles (including the loction ofregions T 30° from an adjacent gap) for a two-pole rotor ECM relying ona single position sensing Hall device will reveal that optimizedstarting performance will be obtainable only with magnets that span360°, 180°, 120°, or 90°, and thus, such rotors should utilize one, two,three, or four magnets (assuming manufacturability considerations arenot of overriding importance). It thus will be understood that ourteachings are that the number of magnets used, and therefore themechanical angular span thereof, should be selected and the location ofmagnetic poles should be selected so that the polar transistor locations(or magnetic nulls) T, will be angularly located thirty degrees fromgaps between adjacent magnetic elements. For completeness of disclosure,we note that the magnet material we used in motor 16 were 0.165 inch(4.19 mm) premolded thick ferrite type S3547 purchased from StackpoleCarbon Co., and that the material purchased was characterized as havinga BR value of 3220 gauss and an HCI value of 4850 oersteds.

[0078] While on the subject of the rotor magnets, we have alsodetermined that the density of the magnetic ceramic material appears tobe of extraordinary importance in motor applications where the magnetsare exposed to both moisture and freezing temperatures. We havedetermined that the material used should be sufficiently dense, ornon-porous, that the magnets do not crumble and break because ofmoisture freezing therein. It is presently believed that the ferritematerial described above should have low porosity, equivalent to thatassociated with a density of at least about 4.8 grams per cubiccentimeter.

[0079] With continued reference to FIG. 11, we have found that thestarting performance of motor 16 is sensitive to the reluctance torqueof the motor which in turn is affected by the size and location of thereluctance steps in the bore. With respect to starting torque problems,the transition T between north and south rotor poles has a larger affecton reluctance torque (and thus starting torque) than the gaps betweenthe magnet segments 316, 317, and 318; and the reaction of thistransition magnetic region to the stator gaps 337, 339, 341 and steps429, 430, 431 creates a major portion of the reluctance torque. A numberof published works describe the phenomena of reluctance torque, one ofthem being the book titled Permanent-Magnet and Brushless DC Motors byT. Kenjo and S. Nagamori, published by Oxford University Press, WaltonStreet, Oxford OX2 6DP, having a copyright date of 1985, the contents ofwhich are incorporated herein by reference for background purposes. Weutilize this phenomena, and distort the air gap (with steps) so that itis not a uniform air gap around the full circumference of the bore.

[0080] We have found that improved starting performance of motor 16results when the depth of steps 431 and 439 are from 0.025″ to 0.050″(0.63 to 1.27 mm), and preferably 1.27 mm; and when the arcuate spanstheta are from 40° to 50°, and preferably 40°. To give a general idea ofthe improvements in starting torque that may be attained when followingthe teachings presented herein, we have found that motors like motor 16having steps of about 1.27 mm and an arcuate extent of 40° have from twoto four times as much locked rotor torque as that available fromsimilarly sized, shaded pole, C-frame, AC induction motors.

[0081] It should now be understood that we have found that undesirablereluctance torque sensitivity and potential starting performance andtorque problems can be avoided and be made relatively independent of thelocation of transition regions T relative to device 439 when the rotor54 is at rest.

[0082] While we have built satisfactory rotors, for use with motorsembodying the present invention, having more than three arcuatecircumferential permanent magnets (e.g., with 6 magnets), three (3)arcuate magnets is our preferred alternative, based on economicconsiderations. Also for the purpose of making a full and completedisclosure, it is noted that the physical gaps 337, 339 and 341, areshown exaggerated in FIG. 11, and that the magnets have chamfered orbeveled corners (see 343, 345), as shown, at their edges remote fromaxis of rotation 347 to facilitate fabrication of rotor 300, and tominimize magnet chipping or breakage in the region of the gaps duringrotor fabrication.

[0083] Because of the stepped stator bore 425 of the stator, when themotor is started (i.e., first energized) a magnetic field is establishedabout the bore such that there are magnetic flux differences about thebore, which assists in initiating rotation of the rotor. Once the rotorstarts turning, the device 439 senses rotor rotation and controlscommutation of the windings 59 and 61 in a manner to establish arotating magnetic field (in the stator), and operation of the motor asdescribed in detail below and in the aforesaid U.S. patent applicationSer. Nos. 07/661,807 and 07/661,818.

[0084] A grounding pin 362 (see FIGS. 5 and 20) is staked to the statorcore 360 and upon positioning of the evaporator fan motor on circuitboard 336, pin 362 passes through circuit board hole 364. The pincontacts and is soldered to ground lead 3 on the board. Other elementsthat support and anchor the motor to the board are molded, molded bobbinsupports 368, 384 (previously discussed), and the electrical contactpins or projections 498, previously discussed, which are connected tothe winding coil leads.

[0085] Thus, the motor and control circuit are mutually interdependentlypositioned, supported, secured, and electrically connected through aplurality of cooperating members. Also, the Hall device, mounted on thecircuit board, is precisely located in operative relationship within thestator core; and magnetically coupled to the rotor flux while beingcontained within a stator core pocket. It should be particularly notedthat no nuts or bolts are required for the assembly illustrated herein.

[0086]FIGS. 4, 5 and 16-19 show features of the housing 50 that furtherassist in the positioning, securing, and insulation of the motor andcontrol circuit 1. Referring first to FIGS. 18 and 17, note that a pairof tapered positioning ribs 503 are formed integral with the housing 50.The positioning ribs 503 taper toward the central region of the assemblycover 50 and may be molded to the desired final shape or molded and thenshaped or formed by an upset tool passing through access holes 505 alsomolded in the bottom of the cover. When the motor and control assemblyis inserted into the housing 50, the positioning ribs 503 contact thesides of the stator core 360 (see FIGS. 5 and 19) and guide the assemblyinto a desired predetermined centralized position where it is spacedfrom the sides of cover 50. The ribs also prevent the motor, after beingsecured in the housing 50, from subsequent undesired lateral movement.

[0087] The ledges or shelves 507 (best shown in FIGS. 18 and 19) nearthe bottom 102 of the housing 50 provide positioning and support meansfor the mating corner notches 502 molded integrally in the bobbin 56(see FIGS. 12 and 19). The housing 50 also assists in positioning andsecuring the motor and control by means of mating slots 78, 80; andtapered camming fasteners 73, 75 as described above.

[0088]FIG. 21 shows pulsing, sampling, control, and protective circuitsutilized with the Hall device 439. Capacitor 135 provides a seriescapacitance which acts as an impedance to drop the voltage from thehigh-voltage bridge rectifier 128 (which is part of the power supplythat powers the stator windings 59 and 61 as described below) to providea lower operating voltage for the ASIC 200 semiconductor integratedcircuit, associated electronic circuits, and the Hall sensor 439. Thelow-voltage electronic power supply 125 (which receives its powerthrough capacitor 135) includes diodes 132 and 134 and provideslow-voltage rectified DC power. The low-voltage power supply 125 alsoincludes filter capacitor 129, across diodes 132, 134, which smooths theDC output voltage, and helps absorb line transients and transientsgenerated by switching circuits described below. A voltage regulator 136in parallel with filter capacitor 129 provides a regulated voltage ofapproximately 8.7 volts to the electronic circuitry. A MOV (metal oxidevaristor) 120 is positioned across the input lines 36, 37 to providetransient protection for the circuit. As will be understood, MOV 120will exhibit high resistance at low voltage (e.g., 120V), and lowresistance at high voltages.

[0089] Resistors 138 and 140 are also part of the low-voltage powersupply 125 and are connected between capacitor 142 (the high-voltagefilter capacitor) and capacitor 129 (the low-voltage filter capacitor)to bleed current into the low-voltage power supply 125. Bleeding ofcurrent is required in the event the motor windings 59 and 61 of theevaporator fan motor 16 are unenergized, or become deenergized. Undersuch conditions, if there were no bleed circuit, no current would bedrawn from capacitor 142, and this condition would result in a voltagedoubling circuit between capacitor 135 and capacitor 142 (in which thevoltage on capacitor 142 would go to twice the peak of the voltagebetween lines 36, 37, while at the same time current to capacitor 135would be reduced). This could result in insufficient current to supplythe electronics and ASIC 200, which could render inoperative the controlcircuit, including the protective current limiting and timed motor startand restart operations. Accordingly, resistors 138 and 140 are providedto bleed current through the capacitors 129 and 142 so that the voltageon capacitor 142 cannot become excessive, and the power to the controlcircuits insufficient.

[0090] The current bled requires only a small amount of power becauseresistors 138 and 140 are large. Also, since the capacitor 135 currentis decreasing as the voltage on capacitor 142 is increasing, the currentflow through resisters 138 and 140 will be increasing. This tends tostabilize the power capability of the low-voltage power supply 125 underconditions in which the windings are not energized. Under a stallcondition, the protective circuitry of ASIC 200 will shut off currentflow to the motor windings in order to protect the motor, as describedbelow.

[0091] Resistor 144 is a current-limiting resistor that limits theinrush current when power is applied to the control circuit, and alsoprevents large surges of current in response to voltage surges in thepower lines 36, 37. A MOV (metal oxide varistor) 120 is also providedacross the power lines 36, 37 as a transient suppressor to absorb powerline transients. Connections or pins 1 and 2 of ASIC 200 are connectedto the Hall device 439 while pin 4 is grounded. H+ (pin 2) powers theHall device 439, while HO (pin 1) of ASIC 200 is the output of the Halldevice sensed by the ASIC. The Hall device 439 has a high output signalwhen coupled to one polarity of flux from rotor 54 and a low output withthe reverse polarity of flux. The Hall device 439 is pulsed by ASIC 200as described below in connection with FIG. 22 for 5 microseconds.

[0092] The ASIC senses the state of the Hall device, and then turns offthe power to the Hall device for some 35 microseconds, with the Halldevice power averaging only {fraction (1/8)} of the normal powerrequired for a continuously energized Hall device.

[0093] Resistor 130 and capacitor 131 establish an RC time constant thatdetermines the frequency of the oscillator or clock timing in ASIC 200(as described below in connection with FIG. 22), thereby controlling thetime the Hall device 439 is powered on. This RC time constant alsodetermines the timing for the protective start-restart circuit ofevaporator fan motor 16 (also discussed below), which protects the motor16 in the event of a stall. Still further this RC time constant controlsthe timing for the ASIC 200 logic circuits, and the pulse widthmodulation (PWM) frequency used during high current conditions.

[0094] Pins 5 and 6 of ASIC 200 provide signals to drive or turn thefield effect transistor (FET) switches 154 and 156 on and off, ascontrolled by the ASIC logic in order to control current flow to, andthrough, the windings of the motor. Pins 5 and 6 of ASIC 200 areconnected through resistor 146 and tab 150, and resistor 148 and tab152, respectively, to the FET switches 154 and 156, respectively. Thetabs 150 and 152 are essentially jumpers which can be selectivelyremoved and alternatively inserted instead into the tab openings 162 and164, respectively, thereby to selectively change the direction ofenergization of the windings 59 and 61, in order to change the directionof rotation of the motor for applications where a reversed direction ofrotation is desired. Resistor 170 is a motor current shunt resistor thatmeasures or senses the current supplied to motor 16, and this resistordevelops a signal responsive to such current which is supplied to ASIC200 through resistor 172. This motor current signal is provided to ASIC200 between pins 7 and 4, and is utilized by the ASIC to sense anovercurrent condition, and thus detect motor stalling. In response tosuch signals, the ASIC limits the power supplied to the motor duringstarting conditions. High motor current could result, for example, froma motor stall condition, and could cause demagnetization of thepermanent magnets on the rotor. ASIC 200 limits the motor current, aspart of the motor stall protection (as described in more detail below)and will also limit power to the motor in the event that capacitor 127fails or shorts.

[0095]FIG. 21 also shows the high efficiency power coupling circuit forevaporator fan motor 16. The 115-volt alternating current (AC) lines 36and 37 are connected through capacitor 127 in power line 36 to the fullwave rectifier bridge circuit 128 of the high-voltage power supply.Filter capacitor 142 is connected across bridge circuit 128, and pulsedpower is supplied to the motor windings 59 and 61 through FETs (fieldeffect transistors) 154, 156 as controlled by the control circuit whichincludes Hall device 439 and ASIC 200. Capacitor 127 effectivelycontrols the power input to the coil windings 59 and 61. For example,changing the size of capacitor 127 changes the amount of power suppliedto the motor. Thus, the size of capacitor 127 can be selected toselectively vary the power output of the motor 16 (by varying the inputpower) over a reasonable range without the necessity of making anychange in the motor itself (e.g., changing the windings thereof).Variations in the capacitance of capacitor 127 can provide, for example,changes in motor power output of plus or minus 10%. An example of thiscan be better appreciated by reviewing the data for motors 1 and 2 inTable I hereinabove, wherein a change in size of capacitor 127 alonecauses a change of about 4.5% in power output.

[0096] If capacitor 127 is made smaller, there will be a higherimpedance in the AC power supply, and less power to the motor results,which will cause the motor to run slower under a fixed load condition.Since the tolerances and temperature performances of standard commercialcapacitors are quite good, there is only a small temperature coefficienteffect, and as a result very little temperature drift problems areassociated with relying on capacitor control of motor output. Unlikecapacitors, permanent magnets (such as in the rotor 54) have relativelylarge temperature coefficients, which tend to provide non-uniform motorperformance through relatively large variations in the magnetic fluxassociated with variations in temperature. The use and selection of thecapacitance of capacitor 127 for control purposes tends to provide moreuniform motor speed even when there are temperature associatedvariations in the magnetic flux of motor 16.

[0097] Capacitor 127 also limits the voltage supplied to, and the powerinto, evaporator fan motor 16, and thus helps increase the powerefficiency of the motor, while at the same time substantially providingdesired motor speed, even when there are changes of magnetic flux in therotor because of temperature changes. While the resultant power savingmay be small in many cases, it contributes to the overall improvedefficiency of the motor 16, and is cost effective over the normally longoperating life of motor 16 when it is used in an application such as ahousehold refrigeration system.

[0098] Limitation on the voltage (in the circuit described) alsoprotects the motor 16 from over-voltage conditions resulting from powerline surges. Also, the use of capacitor 127 results in requiring motorwindings made of fewer turns of larger wire. If other things were keptequal, omission of capacitor 127 would mean that the winding of motor 16having a given power output would be made of an increased number ofturns which would require the use of much smaller diameter wire.However, when capacitor 127 is provided as described, fewer turns of alarger diameter wire were required, minimizing the time and expenserequired to wind the winding coils for the motor, and making the motormore manufacturable.

[0099] Capacitor 127 in the input power circuit also acts as aprotective device against damaging current flow in the event of a shortin the control circuit, or upon stalling of the evaporator fan motorunder abnormal load conditions. It will be understood that a DC motor,upon stalling, does not generate any back emf, and will draw excessivepower. The excessive power may be as high as 20-30 watts for motors suchas the specific motor 16 described herein, and such an overload canresult in overheating, and possible damage to the motor, andparticularly to the windings 59, 61. While various devices such asthermal protective devices or cutouts could be used in series with theAC power lines 36, 37, the capacitor 127 will limit the power toevaporator fan motor 16 such that the fan motor 16 input power actuallydrops, under stall conditions, to about 1.5 watts, with a temperaturerise on the order of less than 4° C. (rather than on the order of up to50° C. in more conventional evaporator fan motors under suchconditions).

[0100] Additional motor protective means provided in the presentinvention include motor current limiting and a timed start-restart(operable during fault conditions such as motor stall), and aredescribed below. These means cooperate to further protect the evaporatorfan motor 16.

[0101]FIGS. 22A, 22B and 22C collectively show the “Application SpecificIntegrated Circuit” device (ASIC) 200. FIG. 22 shows the connectiverelationship of the circuit portions shown in FIGS. 22A, 22B, and 22C.Thus, in FIG. 22A, the circuit lines, conductors, or connectionsnumbered 1113 a, 1114 a, 1115 a, 1116 a match to, and are a continuationof, similar lines or connections 1113 b, 1114 b, 1115 b and 1116 b,respectively, at the top of FIG. 22B. Similarly, the lines orconnections 1116 b, 1117 b, 1118 b, 1119 b, 1120 b, 1121 b, 1122 b and1123 b at the right side of FIG. 22B match to lines or connections 1116c, 1117 c, 1118 c, 1119 c, 11120 c and 11121 c at the left side of FIG.22C. As described above, ASIC 200 is connected in circuit with the Halldevice 439 and motor windings 59 and 61 as shown in FIG. 21. The seriestiming circuit including resistor 130 and capacitor 131 discussed aboveare also connected to ASIC 200.

[0102] In FIGS. 22A, B, C, the circuitry and related logic functions ofthe component parts, circuit elements, or building blocks, forming thecircuit of ASIC are described and shown herein consistent with thecircuit element identification set forth in the RCA Solid State “CMOSIntegrated Circuits” Databook SSD-250C (Copyright 1983 by RCACorporation, printed in USA 8-83), and in particular the identificationfor the 4000 Series CMOS Logic. The identifying characters associatedwith each of the principal circuit elements in FIGS. 22A, B, C identifyits specifics in accordance with the just mentioned Databook(hereinafter simply referred to as the CMOS Databook). For example,flip-flop 1202 of FIG. 22A includes the identifying number 4013. Thenumber 4013 indicates that it is part of the 4000 Series CMOS Logicspecified in the CMOS Databook, which book is utilized by majorintegrated circuit manufacturers such as Motorola and Harris, and thecontents of which book is hereby incorporated by reference.

[0103] While the complete identification for flip-flop 202 in the CMOSDatabook would be CD4O13B, the associated prefix and suffix letters(e.g., “CD” and “B”) for each of the circuit elements are not used inFIG. 22. However, reference to the CMOS Databook provides thespecifications, performance, and characteristics of a type 4013flip-flop 1202 which would enable a competent integrated circuitmanufacturer to reproduce this flip-flop circuit as well as the othercircuit elements identified in FIG. 22. In an actual reduction topractice of the present invention, integrated CMOS (Complementary MetalOxide Semiconductor) circuits used as ASIC 200 were made by IntegratedCircuit Systems, Inc. of Valley Forge, Pa. based on the informationcontained in FIG. 22.

[0104] In FIG. 22A, ASIC 200 provides the basic timing signals by meansof oscillator clock circuit 1210 whose time constant or frequency isdetermined by the external resistor 30 and capacitor 131 RC network(shown in FIG. 21, and also shown to the left of FIG. 22A). This clockcircuit energizes the Hall device for five microsecond pulses. As bestappreciated by considering FIG. 21 together with FIG. 22A, junction 1201of resistor 130 and capacitor 131 is connected to ASIC 200 by a singlepin.

[0105] With focus now on FIG. 22a, a voltage dividing circuit consistingof resistors 1203, 1205, and 1207 is provided in the input circuit ofcomparators 1206 and 1208, which are the same as National Semiconductorcomparators, part LN393. For this reason comparators 1206 and 1208 aredesignated as type 393 in FIG. 22A. The comparators 1206 and 1208provide the input to the flip-flop circuits 1202 and 1204, which in turnprovide the basic timing and control signals for the logic operation ofthe circuit. It is to be noted that in FIGS. 21 and 22 the values of thecomponent resistors and capacitors are set forth in the respectiveschematic drawings for the sake of completeness of disclosure, and thatthe appropriate values for those devices would be easily determinable bya person skilled in the art.

[0106] The Hall driver and decoder circuit 1220 (see the left-hand partof FIG. 22B) includes the flip-flops 1222 and 1224 which, likeflip-flops 1202 and 1204, are type 4013, and buffers 1221, 1223 and 1225(all of which are type 4049). The output of buffers 1223 and 1225 isconnected to the Hall sensor 439 plus terminal via line 1140 to providethe pulses which energize the Hall sensor, while the input of theflip-flop 1224 is connected to the Hall output terminal via line 1141.

[0107] The pulsing and sampling circuitry of FIG. 22 energizes the Hallsensor 439 for 5 microseconds out of every 40 microseconds, providing aduty or power cycle which is only some {fraction (5/40)} or {fraction(1/8)} of the case if the Hall sensor were to be energized and operatedcontinuously. Sensing or sampling the Hall sensor 439 during such “onperiods” is adequate to provide an indication of polarity or position ofrotor 54 for switching or commutating power supplied to the motorwindings 59, 61. When desired, the timing and sampling periods may bevaried or adjusted for motors operating at different speed ranges byproving a different oscillator frequency for clock circuit 1210. Asshould be understood, this may be accomplished by using different valuesfor external capacitor 131 and resistor 130, or by using differentdivider networks. In an actual reduction to practice, the power requiredby Hall sensor 439 was significantly reduced from 4 milliamps(continuous operation) to 0.5 milliamps ({fraction (1/8)} duty cycle),and this would permit a significant reduction in the size of the powersupply 125 (which powers ASIC 200 and Hall sensor 439).

[0108] The Hall sensor output is used as a control signal to trigger thesequential energization of the stator windings 59 and 61 of theevaporator fan motor 16 through FET switches 154 and 156 (see FIG. 21).Sequential energization of the stator windings provides a rotatingmagnetic field which reacts with the permanent magnetic field of therotor 54, and provides the torque which causes rotation of the rotor,and hence mechanical power output at the rotor shaft (more details ofwhich are described in the above-referenced copending U.S. patentapplication Ser. Nos. 07/661,807 and 07/661,818).

[0109] Although magnetic flux created by an energized winding isproportional to current flow through the winding, during operation ofthe motor 16, maximum torque, and hence maximum power output, is notcontinuously produced during continuous maximum current flow through thewindings 59 and 61. This result occurs because motor torque and poweroutput are proportional not only to the magnetic flux in the motorwindings, but also to the effective flux coupling between the windingsand the rotor 54. Changes in magnetic flux coupling result in decreasedmotor torque during a portion of rotor rotation, notwithstanding thecontinuous application of full power to the stator windings. Thisphenomena can be better understood by referring to FIG. 23.

[0110]FIG. 23 shows two plots—one of current flow through (proportionalto magnetic flux) windings 59 and 61 against time; and the other oftorque or power output plotted against time. As shown by curve 1100,current flow is in the form of a square wave and the curve 1101 is alsofairly representative of applied or input power. However, the torqueproduced (and hence output power) falls off at the end of each cycle ofinput current or power, as shown in portion 1103 of curve 1101. Thereduced motor power output during the periods 1103 occur because ofvariations in the magnetic coupling between the rotor and statorwindings, and the duration of periods 103 is about 20-30 percent of thetotal power input time represented by curve 1100. We have determinedthat significant power savings can be made with little or no sacrificein output performance, by switching off the input power during the lowtorque-to-current periods 1103 with sub-circuits shown in FIGS. 22B and22C.

[0111] In FIGS. 22B and 22C, the circuitry there shown calculates adesired correct turnoff signal over a wide range of motor speeds inaccordance with the present invention. The turnoff signal controlsenergization of the motor windings as a function of relative rotorposition, notwithstanding that the Hall sensor 539, may be indicatingthat continuous power should be supplied to the motor windings.

[0112] More specifically, the commutation turnoff circuit 1230calculates when a winding should be turned off to enhance the efficiencyof the motor, and includes several parts. A commutation time counterincludes counters 1231 (see FIG. 22C) and 1232 (types 4040 and 4024,respectively) which count the oscillations provided by the oscillatorclock 1210 and thus time the interval between commutations, and alsotime the pulse width modulation frequency during operation of currentlimiting circuit 1260 and the timed start retry circuit 1270 (all asdescribed hereinbelow). Switching action is provided by digital latchcircuits 1233, 1234, and 1235 (each type 4175) to hold the value of thelength of time of the last, or previous, commutation period. That is,the circuit looks at the number of input pulses to the counters, andstores the number of input pulses in digital latch circuits 1233, 1234and 1235.

[0113] The adders 1236, 1237 and 1238 (each of which are type 4008)calculate a period which is approximately {fraction (3/4)} of the valueheld in the latch circuits 1233, 1234 and 1235 by adding together thevalue of the latch (but shifted two bits toward the Lsb) and the valueof the latch shifted one bit toward the Lsb. A digital comparatorincludes the individual digital comparators 1239, 1240, and 1241 whichcompare the values of the adders 1236, 1237, and 1238 to the real timecount of the counter 1233. During normal running conditions, when thecount equals the adder 1236, 1237, and 1238 output, the motor windingsare commutated off. The adders 1236, 1237, and 1238 add A to B, andtheir inputs are connected such that they perform as one unit. Thedigital comparators 1239, 1241, and 1242 in effect compare thepreselected numbers A to B, and when the numbers A and B are equal, thedigital comparators provide a control pulse.

[0114] Circuit 1250 (see FIG. 22B) includes NAND gates 1251 and 1252(both of which are type 4011) and flip-flop 1253 (type 4013) which holdthe gate drives in the off condition until the next commutation, oralternatively until pin Q12 of counter 1231 goes high. When pin Q12 ofcounter 1231 goes high, indicating that the motor is either stalled orrunning very slowly, flip-flop 1253 turns the windings 59 and 61 backon, so that motor starting torque is maintained.

[0115] Under conditions of motor stall or some other condition when themotor speed is very low (i.e., substantially below the speed developedduring normal running conditions), excessive currents could flow throughthe motor windings 59 and 61. As mentioned above, normal rotation of therotor develops a back emf in the motor windings which opposes theapplied emf, or line voltage, to effectively limit current flow throughthe windings during normal operating conditions. However, under stalledor abnormally slow running conditions, the back emf is substantiallybelow that developed during normal running conditions. While capacitor127 would normally limit motor current under such conditions, ifcapacitor 127 fails in a shorted condition the desired current limitingaction would not take place. Therefore, additional current limitingmeans are provided to limit the amount of current flow through the motorwindings thereby to protect the motor from overheating and possibleresultant damage.

[0116] The current limiting circuit 1260 (see FIG. 22A) controls thecurrent through the motor windings as set by (see FIG. 21) resistor 170which is in series with the switching circuit 157. Whenever the motorwinding current exceeds the predetermined limit, the gate drives for thepower switches (FETS) are forced to zero. Flip-flop 1261 (type 4013)blanks the operation of the current limit operation for intervals oftime that the switches (FETs) could possibly turn on, with everythingsynchronized to the timing signals provided by the oscillator clock1210. As a result, short turn-on transients are ignored by the currentlimiting circuit 1260. The action of the gate drive is reenabled by thesignal Q4 (supplied via lines 1116 c, 1116 b, 1116 a) of the clock resetcounter 1231 (see FIG. 22C), setting the basic pulse width modulationfrequency.

[0117] Current limiting by current limiting circuit 1260 is providedduring starting, during motor stall conditions, and in the event offailure of capacitor 127, This is done to provide thermal overloadprotection during fault conditions, and to also prevent demagnetizing ofthe motor rotor magnets during normal starting conditions if lowcoercivity magnets are used in the rotor. The current limiting circuit1260 thus limits the magnitude of the current allowed to energize themotor windings by inhibiting or blanking the energization for thewindings to prevent motor overheating.

[0118] The motor protective start retry circuit 1270 (see FIG. 22B)includes the NOR gate 1271 (type 4025) and provides periodicenergization of the evaporator fan motor 16 to restart the motor aftercircuit 1270 shuts the motor off if a commutation, or normal runningspeed, is not achieved in a predetermined time. The predetermined timeis set by counter inputs to NOR gate 1271. The motor 16 is turned on bythis same gate, and with the input shown, the motor is shut off if nocommutation is sensed by NOR gate 1271 (after a predetermined time, suchas, for example, 0.16 seconds). A motor start retry of 0.25 secondsduration occurs every 1.38 seconds. Thus, the motor is not continuouslyenergized in the event starting (i.e., if commutation) is not achieved,and a periodic retry cycle is provided to reduce motor heating when therotor is stalled. It is believed that pulsed retry periods will oftenresult in starting of stalled motors, and significantly more startingtorque is provided from the motor 16 than would be the case with ashaded pole motor. It should also be understood in connection with theabove discussion that the Hall device output signal appears betweenground and the Hall device output line 1141.

[0119] Use of the various multifunction, multi-purpose componentsdescribed herein permit easy and economical assembly. Traditional “nutsand bolts” have not been used, and the components of the motor andcontrol assembly herein shown are readily assembled without specialtools, jigs, or fixturing.

[0120] Also, and as described above in connection with FIGS. 21-23, thecontrol circuit, once operatively connected to the motor 16, results ina motor having reduced power requirements (because of pulsing of theHall device, and limited periodic energization of coil windings 59 and61 during periods of greatest power). In addition to greatly increasingthe overall power efficiency of the motor, this also enables the use ofsmaller power supplies. The circuitry and motor construction hereindescribed further provides significant desirable protective andoperational features, including impedance stall protection, overheatingand burnout protection, resistance to moisture, and start-restartoperation in the event of stall or other abnormalities. Still further,we provide desirable means to easily modify or control the power outputof the motor over a limited range, and to reverse the direction ofrotation of the motor.

[0121] The integrated motor and control assembly herein shown requiresfew parts (which minimize manufacturing costs, including the cost ofmaterials and labor), and the costs and number of components which mustbe maintained for spare parts or replacement purposes.

[0122] Application of our inventions can result in simple, powerefficient, motor and control assemblies that are readily manufacturable,and that have desirable operating characteristics and operationalfeatures. These assemblies may be compact in size and capable of fittingwithin the space available in existing designs of refrigeration systemsto permit their ready use as a repair or replacement unit, or forincorporation into the original manufacture of systems built accordingto existing designs.

[0123] A specific embodiment of the present invention has been describedprimarily in connection with a single-phase, two-pole DC brushlessmotor. However, many of our improvements may be applied to d.c.brushless motors with poles and or winding stages greater than two.Also, while a preferred embodiment of the invention has been describedin connection with a refrigeration system evaporator fan motorapplication, principles of our invention clearly may be applied tomotors for other applications, and particularly to other high efficiencyapplications.

[0124] It is to be specifically understood that a motor and control asdescribed herein advantageously may be used for refrigeration condenserfan applications, although changes from the product illustrated hereinmost likely should be made. For example, a larger motor shaft andbearings having increased load carrying capacity would likely bedesirable. Also, the motor and control desirably would be protected fromthe dusty and dirty environment usually encountered by condenser fanmotors in a manner better than what would be expected from the housing50 alone, which has a number of dust admitting openings therein. Motorsbuilt as taught herein may also be used for non-refrigeration systemapplications. As one such example, motors could be built as taughtherein for use as 50 watt output draft inducer fan motors, withessentially the only desirable change being to eliminate the seriescapacitor for cost reasons (and also because redundant current limitingwould not be required).

[0125] Accordingly, while the present invention has been described inconnection with preferred embodiments, variations will be readilyapparent to those skilled in the art from reading the foregoingdescription and it is to be clearly understood that this description ispresented by way of example, and not for purposes of limitation.

What we claim as new and desire to secure by Letters Patent of theUnited States is:
 1. A high-efficiency low-power integrated and unitaryfan motor and control assembly suitable for use in refrigeration systemscomprising an electronically commutated DC motor, a control and powercircuit, and a substrate carrying a plurality of electronic componentsand interconnections of such circuit; said electronically commutatedmotor including a C-frame stator core, a permanent magnet rotor, and atleast one winding inductively coupled with said stator core; a Hallsensor mounted on said substrate and forming part of said circuit, andpositioned in magnetic coupling relationship with said permanent magnetrotor to sense rotation of said rotor; said circuit including at leastone DC power supply, and switching means to provide power to said atleast one winding in response to signals from said Hall device; and saidcontrol circuit including means to inhibit the supply of power to saidat least one winding during a portion of each revolution of the rotorthat corresponds to reduced magnetic coupling between the rotor andstator, thereby to decrease the total amount of power supplied to the atleast one winding and to increase the efficiency of the motor andcontrol.
 2. The motor and control assembly of claim 1 wherein said motorincludes a bobbin that carries the at least one winding, and theassembly includes means that relatively position and interconnect saidmotor and electronic components, and said bobbin includes means thatposition and secure the bobbin on the substrate and that also provideelectrical connections to said circuit.
 3. The motor and controlassembly of claim 2 wherein said means that secure said bobbin to saidsubstrate includes electrical terminals to which said at least onewinding is connected, and wherein said terminals pass through openingsin the substrate and are soldered to said circuit board.
 4. The motorand control assembly of claim 3 wherein said means that secure saidbobbin to said substrate further includes at least one positioningsupport integral with said bobbin which extends outward from the bobbinin the same general direction as said terminals.
 5. The motor andcontrol assembly of claim 2 wherein the assembly further includes aninsulating housing that positions and supports the motor and saidsubstrate therewithin, and that electrically isolates said electroniccomponents.
 6. The motor and control assembly of claim 8 wherein saidbobbin further includes at least one tapered camming member; saidhousing includes a slot positioned to receive said at least one cammingmember; and wherein said at least one camming member is configured toresiliently deform said housing until said at least one camming memberenters said at least one slot thereby to detachably retain said bobbinand substrate in a predetermined position within said housing.
 7. Themotor and control assembly of claim 5 wherein said housing includes ahinged cover with latches thereon and also includes latch holders; saidcover being hinged over at least a portion of the portion and controland being latched in place thereby to enclose and isolate at least someof said electronic components.
 8. The motor and control assembly ofclaim 3 wherein said motor includes a pair of oil well covers; thesubstrate includes an oil well cover accommodating opening in a portionthereof; the housing includes an oil well cover accommodating opening;and the oil well cover includes a portion that passes through saidportion of the substrate and is retained in said accommodating openingof the housing.
 9. The motor and control assembly of claim 8 wherein:said housing includes a number of resilient fingers extending about saidaccommodating opening; and wherein said resilient fingers grasp andsecure said oil well cover in assembled relation therewith.
 10. Themotor and control assembly of claim 9 wherein the motor includes asecond oil well cover, and wherein said oil well covers include portionsthat protrude from the housing and thereby provide means for suspendingthe assembly in the equipment with which it is to be used.
 11. The motorand control assembly of claim 1 wherein: said substrate comprise acircuit board that includes a grounding pin receiving aperture; agrounding pin is mechanically and electrically secured to said statorcore and to a run on the circuit board adjacent to said receivingaperture; said grounding pin providing electrical grounding between saidmotor and the control and power circuit while also relativelypositioning, securing and supporting said motor and circuit board. 12.The motor and control assembly of claim 1 wherein wherein the substrateincludes a circuit board having a printed circuit thereon; said printedcircuit including a pattern of connectors for mating with an edgeconnector plug; said assembly further including a housing having anopening adjacent said pattern of connectors, and also having means forpositioning and guiding an edge connector plug into electrical contactwith said pattern of connectors.
 13. The motor and control assembly ofclaim 1 wherein said core includes an axially extending chamber integraltherewith, a holder for said Hall sensor is positioned within saidchamber, and said Hall sensor is positioned within said holder; the Halldevice holder including positioning means integral therewith which aresecured to the substrate; and electrical leads from the Hall sensor aresoldered to circuitry on the substrate.
 14. The motor and controlassembly of claim 13 wherein the Hall device holder includes a shoulderintegral therewith for contacting, spacing and supporting said statorcore with respect to the substrate.
 15. A high-efficiency integratedevaporator fan motor and control assembly particularly adapted for usein refrigeration equipment to circulate air within a refrigerated spacecomprising: an electronically commutated DC motor; a circuit boardincluding a plurality of electronic components and interconnectionstherebetween; said electronically commutated motor including a statorcore, a permanent magnet rotor and at least one winding magneticallycoupled to said stator core; a housing having means for positioning andsupporting said motor and electronic components; a sensor, for sensingrotation of said rotor, connected in circuit with the interconnectionsof said circuit board and positioned in magnetic coupling relationshipwith said permanent magnet rotor; said electronic components including aDC power supply, and switching means to provide power from said DC powersupply to said at least one winding in response to signals from saidHall device; said stator core being of the C-frame type; and said rotorincluding means for surrounding and containing the permanent magnets.16. The motor and control assembly of claim 15 wherein the housingincludes an opening enabling an edge connector plug to pass therethroughfor contact with conductors on said circuit board.
 17. A high-efficiencylow-power integrated evaporator fan motor and control assemblyparticularly adapted for use in a refrigerated environment to circulatecooling air within the environment, the assembly comprising: anelectronically commutated DC motor; a circuit board including aplurality of electronic components and interconnections thereof; saidelectronically commutated motor including a stator core, a permanentmagnet rotor and at least one winding wound on a multifunction bobbinand magnetically coupled to said stator core; said bobbin beingpositioned on and connected with said circuit board; housing meanspositioning and supporting said motor and electronic componentstherewithin; and a Hall sensor connected to components on said circuitboard and positioned in magnetic coupling relationship with saidpermanent magnet rotor to sense rotation thereof; said assemblyincluding a DC power supply, and switching means to provide power fromsaid DC power supply to said at least one or more winding in response tosignals from said Hall sensor; and said control circuit including meansto pulse the energizing power supplied to said windings through saidswitching means, thereby to decrease the energizing power and toincrease the power efficiency of said assembly.
 18. The assembly ofclaim 17 wherein said rotor is encased within a stainless steel cupclosed at the open end thereof by a stainless steel disk.
 19. Theassembly of claim 18 wherein said housing includes a bottom having anopening therein and slots which extend from said opening to formresilient fingers between said slots; said motor includes an oil wellcover dimensioned such that said resilient fingers grasp and secure saidoil well cover upon insertion of said assembly into said assembly cover.20. The assembly of claim 19 wherein the motor includes a second oilwell cover and wherein said first oil well cover further includes acylindrical extension which protrudes through the bottom of the housingto enable mounting of said assembly on a support within saidrefrigerated environment.
 21. A motor and control assembly comprising:an electronically commutated DC motor; said electronically commutatedmotor including a stator core, a permanent magnet rotor and at least onewinding magnetically coupled to said stator core; a Hall sensor, forsensing rotation of said rotor, positioned in magnetic couplingrelationship with said permanent magnet rotor; said assembly includingelectronic components, a DC power supply, and switching means fordelivering power from said DC power supply to said at least one windingin response to signals from said Hall sensor; said control assembly alsoincluding means for pulsing energizing power supplied to said Halldevice thereby to decrease the usage of such energizing power and toincrease the efficiency of said assembly; said rotor including aplurality of arcuate magnetic segments secured to a cylindrical core;and an enclosure surrounding said magnetic segments and said cylindricalcore.
 22. The motor and control assembly of claim 21 wherein saidenclosure includes an interference fit metallic cup positioned over saidmagnetic segments and said cylindrical core, and a metallic end plate,with the rim of the open end of said cup extending beyond and rolledover said end plate to secure the magnet segments between the closed endof said cup and said end plate.
 23. An electronically commutatedintegrated motor and control assembly particularly suitable for use inair moving applications comprising: a stator core with at least onewinding disposed thereon; a permanent magnet rotor adapted to rotateabout an axis of rotation in response to rotating magnetic fields in thestator core; means for developing a position control signal indicativeof the rotational position of said rotor; said means for developing aposition control signal including a sensor positioned adjacent the rotorfor generating a control signal responsive to the rotational position ofsaid rotor; means for energizing said at least one winding in apredetermined sequence in response to the position control signal; and acontrol circuit for connecting power, through switching means, toprovide power pulses to periodically energize said at least one windingduring those periods of generation of higher rotational torque, and forinhibiting the supply of power to the at least one winding during atleast part of that portion of each revolution of the rotor that lowerrotational torque is being generated thereby to provide increasedoperating efficiency.
 24. The assembly of claim 23 wherein saidswitching means includes a timing circuit, and wherein said timingcircuit includes an oscillator and divider circuit to provide timingsignals for the operation of said switching means.
 25. The assembly ofclaim 24 wherein said stator core includes a bore in which said rotor isrotatably supported, and the time duration of said power pulses isshorter than the time duration between said power pulses.
 26. Theassembly of claim 25 wherein said bore includes at least two reluctancesteps.
 27. The assembly of claim 26 wherein said steps assist instarting rotation of said rotor upon application of power to said atleast one winding.
 28. The assembly of claim 27 wherein said step is onthe order of at least 1.0 mm.
 29. A motor and control assemblycomprising: a C-frame stator core with a plurality of winding turnsdisposed adjacent said stator core; a permanent magnet rotor includingat least one pair of magnetic poles adapted to rotate in a bore in saidstator core in response to rotating magnetic fields established withinsaid stator core by sequential energization of said winding turns; aHall sensor for developing a position control signal responsive to therotational position of said rotor; means for generating a pulsed controlsignal, responsive to said position control signal, for energization ofwinding turns in a predetermined sequence to provide pulsed torque tosaid rotor; said means to generate said pulsed control signal includingmeans to turn off the energization of selected winding turns during atleast a portion of the period when the rotational torque produced byenergization of said selected winding turns is decreasing from a maximumvalue.
 30. The assembly of claim 29 wherein said portion of the periodduring which the energization of said selected winding turns is turnedoff is approximately 20-30 percent of the total period that energizationof said selected windings would otherwise produce rotational torque. 31.The assembly of claim 29 wherein the energization circuit for saidwinding turns includes a capacitor in series with a source ofalternating current power.
 32. The assembly of claim 31 wherein a fullwave bridge rectifier circuit is connected across the power linesbetween said capacitor and said windings.
 33. The assembly of claim 23wherein said means for energizing said at least one winding in apredetermined sequence includes a capacitor in series with one linearranged for connection to a source of alternating current power. 34.The assembly of claim 33 wherein a full wave bridge rectifier circuit isconnected across the lines arranged for connection to a source of power,and between said capacitor and said windings.
 35. A high-efficiencylow-power electronically commutated integrated motor and control circuitassembly comprising: a C-frame stator core with a plurality of windingsdisposed adjacent said stator core; a permanent magnet rotor adapted torotate about an axis of rotation in response to a rotating magneticfield established within said stator core; means for developing aposition control signal in response to the rotational position of saidrotor; said means for developing a position control signal including aHall sensor positioned in a chamber proximate a bore in said stator coreand responsive to the position of said rotor; means for energizing saidwindings in a predetermined sequence in response to said positioncontrol signal; said means for energizing said windings in apredetermined sequence including lines arranged for connecting to asource of alternating current power through a series capacitor andrectifier in circuit with said alternating current power.
 36. Theassembly of claim 35 wherein said rectifier is a full wave bridgerectifier connected across said lines arranged for connecting a powersource and between said capacitor and said windings.
 37. Thehigh-efficiency low-power electronically commutated motor in accordancewith claim 36 wherein means are provided for turning off theenergization of each of said windings during at least part of a periodwhen the torque produced by said electronically commutated motor woulddecrease as said permanent magnet rotor moves relative to each of theenergized windings.
 38. The assembly of claim 37 wherein said periodsare approximately 20-30 percent of the total time that the energizationof each winding would otherwise provide rotational torque to said rotor.39. The assembly of claim 38 wherein said stator core includes a bore inwhich said rotor rotates, and said bore includes at least one firstarcuate portion positioned about said axis of rotation at a first radialdistance, and at least one other arcuate portion positioned about saidaxis of rotation at a second radial distance, said second radialdistance being greater than said first radial distance and forming astep between said first arcuate portion and the adjacent one of saidother arcuate portion.
 40. The assembly of claim 39 wherein said step isapproximately 0.05 inches.
 41. A method of operating a motor withincreased efficiency, the motor comprising an electronically commutatedmotor having a stator core with a plurality of winding turns disposedabout said stator core, a permanent magnet rotor mounted for rotationabout an axis of rotation within a bore formed in said stator core, anda control circuit for the energization of said windings, the methodcomprising: energizing a Hall sensor with pulses derived from saidcontrol circuit; sensing the output of the Hall sensor during the periodof said pulses to provide a control signal indicative of the angularposition of the permanent magnet rotor; and sequentially energizingwinding turns in response to said control signal in a predeterminedsequence to cause rotation of the rotor; whereby power consumption bysaid assembly is reduced during periods between said pulses of electricpower to the Hall sensor.
 42. The method of claim 41 including theadditional step of providing timing signals to pulse the energizing ofthe Hall sensor.
 43. The method of claim 42 including the steps ofenergizing selected winding turns only during periods of generation ofmaximum rotational torque applied to the rotor, by modifying the controlsignal to de-energize winding turns during periods within which windingturns would produce reduced rotational torque in order to further reducepower consumption by the motor.
 44. The method of energizing anelectronically commutated motor of claim 43 wherein windings arede-energized approximately 20-30 percent of the period that said controlsignal could otherwise cause rotational torque through energization ofthe windings.
 45. The method of claim 43 further comprising the step ofenergizing winding turns through a capacitor provided in series with asource of electric power.
 46. A high-efficiency low-power electronicallycommutated integral motor and control comprising: a stator core with aplurality of windings disposed adjacent said stator core; a permanentmagnet rotor adapted to rotate about an axis of rotation in response toa rotating magnetic field established within said stator core; means fordeveloping a position control signal in response to the rotationalposition of said rotor; said means for developing a position controlsignal including a Hall sensor positioned adjacent said stator core,energized by a source of electrical power, and magnetically coupled tosaid permanent magnet rotor to generate a signal responsive to theposition of said rotor; means for energizing the windings in apredetermined sequence in response to the position control signal; thesource of electrical power being connectable to the Hall sensor throughmeans which provide power pulses to periodically energize the Hallsensor; said power pulses being shorter in duration than the timebetween pulses; and protective means operable during fault conditions toprotect said motor from overheating damage.
 47. The motor and control ofclaim 46 wherein said protective means includes current limiting meansto limit the magnitude of the energizing current for said windings. 48.The invention of claim 47 wherein said current limiting inhibits saidmeans for energizing said windings.
 49. The invention of claim 48wherein said means for energizing said windings is turned off when saidmotor stalls.
 50. The invention of claim 46 wherein said means forenergizing said windings is turned off for a first predetermined timeperiod when a commutation of said motor is not achieved in a secondpredetermined time period after starting, and a retry in starting isperiodically provided through periodic actuation of said means forenergizing said windings.
 51. The invention of claim 50 wherein theretry in said periodic actuation is in the order of 0.15 seconds, andsaid period of time between each retry in starting is in the order of1.25 seconds.
 52. A brushless direct current fan motor and controlcircuit, comprising: a skeleton frame stator core including a bore, anda plurality of winding turns carried by the core; a permanent magnetrotor adapted to rotate about an axis of rotation within said bore inresponse to a rotating magnetic field established about said rotor; asensor for generating a position control signal responsive to theposition of said rotor; means for generating said rotating magneticfield in a predetermined sequence in response to said position controlsignal to cause rotation of said rotor; an integrated control circuitfor pulsing power to said winding turns only during the higherefficiency portion of the periods available for pulsing power to saidwinding turns to obtain rotation of said rotor, and for inhibiting theapplication of power to at least some of the winding turns during atleast part of the periods for pulsing power to said winding turns; saidat least part of the periods comprising intervals of lower magneticcoupling efficiencies between the rotor and stator; an alternatingcurrent power source; a first rectifier circuit to provide directcurrent for the windings of said direct current motor; and a secondrectifier circuit to provide direct current for said control circuit;and means to protect said motor under abnormal operating conditions. 53.The fan motor and control circuit of claim 52 wherein said means toprotect said motor includes a series capacitor arranged for connectionin series with an alternating current power source during energizationof the motor.
 54. The fan motor and control circuit assembly of claim 53wherein a first capacitor is connected across said first rectifiercircuit, a second capacitor is connected across said second rectifiercircuit, and a third capacitor is connected between said first rectifierand said second rectifier circuit.
 55. The fan motor and control circuitof claim 54 wherein a high-resistance bleed circuit is connected betweensaid first rectifier circuit to prevent excessive voltage buildup onsaid first capacitor in the event of a motor stall conduction.
 56. Thefan motor and control circuit of claim 54 wherein said first rectifiercircuit provides a higher voltage than said second rectifier circuit.57. The fan motor and control circuit of claim 56 wherein said firstrectifier circuit is connected through at least one switching circuitconnected to said windings; said at least one switching circuit includestransistor switches; wherein connections in circuit with said transistorswitches and said windings are selectively connectable to reverse thecurrent flow through said windings thereby to reverse the direction ofrotation of said fan motor. The invention of claim 53 wherein saidseries capacitor is selected to provide the desired speed of rotation ofsaid evaporator fan motor.
 59. A refrigeration system comprising acompressor, a refrigerant carrying condenser coil, a refrigerantcarrying evaporator coil, and at least one air moving motor assembly formoving air across at least one of said refrigerant carrying coils; saidair moving motor assembly comprising a brushless DC motor having apermanently magnetizable rotor magnetized to establish at least onenorth and at least one south pole with a magnetic transition regionlocated between adjacent north and south rotor poles, a C-frameferromagnetic stator core defining a rotor accommodating bore, and aplurality of energizable winding turns disposed about a portion of thestator core for establishing alternating north and south magnetic polesin the stator core at locations adjacent to the bore; said stator coreincluding a pocket for receiving a magnetic flux sensing device, andsaid bore having a discontinuity therealong so that magnetic fluxassociated with the rotor is not shielded from the pocket byferromagnetic stator core material; said bore further including at leasttwo stepped regions each having an arcuate extent of thirty-fivedegrees, with the depth of the step in each of the two stepped regionsbeing at least about 1.0 mm; and said bore further having a regionestablishing a magnetic flux path anomoly at a location on the boreopposite the location of the bore discontinuity.
 60. The assembly ofclaim 59 wherein the rotor is comprised of at least three magnetsegments, and wherein any magnetic transition region located along anygiven magnet segment is located at least about 30° from an edge of saidgiven segment.
 61. The system of claim 59 wherein the air moving motorassembly comprises a condenser fan motor and control; said controlincludes motor stall protection means, means for protecting the motorfrom overcurrent conditions, and means for inhibiting the supply ofpower to the motor during a portion of each revolution of the rotorduring at least part of the interval during a revolution thatcorresponds to reduced magnetic coupling between the rotor and stator.62. The system of claim 59 wherein the air moving motor assemblycomprises an evaporator fan motor comprising a core and winding, and acontrol disposed within an insulated enclosure cooled by said systemwherein, for each given watt of input power to said air moving motor,said system must consume additional power in excess of each said givenwatt of input power in order to dissipate the heat produced by each suchgiven watt; said control including a capacitor in series with the motorwinding; said capacitor providing stall protection for the motor andcontributing to increased operating efficiency of the motor.
 63. Anassembly for use as a brushless DC motor having a permanentlymagnetizable rotor magnetized to establish at least one north and atleast one south pole with a magnetic transition region located betweenadjacent north and south rotor poles, a C-frame ferromagnetic statorcore defining a rotor accommodating bore, and a plurality of energizablewinding turns disposed about a portion of the stator core forestablishing alternating north and south magnetic poles in the statorcore at locations adjacent to the bore; said stator core including apocket for receiving a magnetic flux sensing device, and said borehaving a discontinuity therealong so that magnetic flux associated withthe rotor will not be shielded from the pocket by ferromagnetic statorcore material; said rotor comprising at least three circumferentiallyextending magnet segments, and wherein any magnetic polar transitionregion located along any given magnet segment is located at least about30° from an edge of said given segment.
 64. The assembly of claim 63wherein the rotor magnets are contained within a deep drawn one piecestainless steel cup, pressed over the magnets, and having a wallthickness of about 0.15 mm; and wherein the cup is closed at the openend thereof by a stainless steel disk.
 65. The assembly of claim 63wherein the rotor magnets are ferrite material having a density of atleast about 4.8 grams per cubic centimeter.
 66. An assembly for use as abrushless DC motor having a permanently magnetizable rotor magnetized toestablish at least one north and at least one south pole with a magnetictransition region located between adjacent north and south rotor poles,a C-frame ferromagnetic stator core defining a rotor accommodating bore,and a plurality of energizable winding turns disposed about a portion ofthe stator core for establishing alternating north and south magneticpoles in the stator core at locations adjacent to the bore; said windingturns being made from wire having a preselected diameter, and saidwinding turns being of a predetermined number; and said stator corehaving a predetermined stack height; said motor being operable within arange of power outputs with said range being determinable by theconnection of a capacitor, having a capacitance within a predeterminedrange, in series with said winding turns during energization thereof.67. An assembly for use as a brushless DC motor having a permanentlymagnetizable rotor magnetized to establish at least one north and atleast one south pole with a magnetic transition region located betweenadjacent north and south rotor poles, a C-frame ferromagnetic statorcore defining a rotor accommodating bore, and a plurality of energizablewinding turns disposed about a portion of the stator core forestablishing alternating north and south magnetic poles in the statorcore at locations adjacent to the bore; said stator core including apocket for receiving a magnetic flux sensing device, and said borehaving a discontinuity therealong so that magnetic flux associated withthe rotor will not be shielded from the pocket by ferromagnetic statorcore material; said bore further including at least two stepped regionseach having an arcuate extent of thirty-five to forty-five degrees, withthe depth of the step in each of the two stepped regions being at leastabout 1.0 mm; and said bore further having a region establishing amagnetic flux path anomoly at a location on the bore opposite thelocation of the bore discontinuity.
 68. The assembly of claim 67 whereinthe rotor is comprised of at least three magnet segments, and whereinany magnetic transition region located along any given magnet segment islocated at least about 30° from an edge of said given segment.
 69. Theassembly of claim 67 wherein the magnetic anomaly constitutes a sectionof the bore having a non-curvilinear shape.
 70. The assembly of claim 67wherein the plurality of energizable winding turns include two windingcoils that are alternately energizable for establishing the magneticpoles of the stator.
 71. The assembly of claim 67 wherein the assemblyfurther includes a plurality of motor control circuit components and asubstrate to which at least one of said components is mounted; saidcomponents including a rotor position sensing device disposed in saidpocket and also mounted to said substrate, and at least one capacitorarranged to control the power supplied to the energizable winding turns.72. A method of controlling and operating a brushless DC motor, havingwinding means and a permanent magnet rotor, in a high efficiency mode,said method including: supplying power to the winding means primarilyonly during periods of greater operating efficiency during each cycle ofapplied power, and inhibiting the application of power to all of thewinding means during at least part of that segment of each cycle ofapplied power when reduced operating efficiency would otherwise result.73. The method of claim 72 further including the step of supplying powerto the winding means through a capacitor connected in series with thewinding means and thereby dropping the applied voltage supplied to thewinding means.
 74. A method of controlling and operating a brushless DCmotor, having winding means and a permanent magnet rotor, in a highefficiency mode, said method comprising: feeding power to the windingmeans through a capacitor connected in series circuit relationship withthe winding means, and thereby reducing the voltage applied to thewinding means and limiting the level of power applied to the windingmeans.
 75. The invention of claim 72 wherein the brushless DC motor is asingle phase motor having two excitation windings that are sequentiallyenergized during each complete cycle of applied power, and wherein themethod comprises energizing a first one of the windings at the beginningof the first half of an applied power cycle but not energizing thesecond one of the windings, and continuing to energize the first one ofthe windings during a period of greater operating efficiency; inhibitingenergization of the first winding during at least part of the portion ofthe first half of the applied power cycle associated with reducedoperating efficiency and continuing to inhibit energization of thesecond one of the windings until the end of the first half of the powercycle; energizing the second winding at the beginning of the second halfof the applied power cycle and continuing to energize the second windingduring a period of greater operating efficiency; inhibiting energizationof the second winding during at least part of the portion of the secondhalf of the applied power cycle associated with reduced operatingefficiency; and inhibiting energization of the first winding during thesecond half of the applied power cycle; whereby no winding is energizedduring preselected portions of each applied power cycle.